Limits...
Analysis of saccharification in Brachypodium distachyon stems under mild conditions of hydrolysis.

Gomez LD, Bristow JK, Statham ER, McQueen-Mason SJ - Biotechnol Biofuels (2008)

Bottom Line: The non-cellulosic monosaccharide composition of Brachypodium is closely related to grasses of agricultural importance and significantly different from the dicot model Arabidopsis thaliana.Diluted acid pretreatment of stem segments produced significant release of sugars and negatively affected the amount of sugars obtained by enzymatic hydrolysis.Scanning electron microscopy analysis of the treated materials showed progressive exposure of fibrils in the stem segments.

View Article: PubMed Central - HTML - PubMed

Affiliation: CNAP, Department of Biology, University of York, Heslington, York YO10 5YW, UK. ldg3@york.ac.uk

ABSTRACT

Background: Brachypodium distachyon constitutes an excellent model species for grasses. It is a small, easily propagated, temperate grass with a rapid life cycle and a small genome. It is a self-fertile plant that can be transformed with high efficiency using Agrobacteria and callus derived from immature embryos. In addition, considerable genetic and genomic resources are becoming available for this species in the form of mapping populations, large expressed sequence tag collections, T-DNA insertion lines and, in the near future, the complete genome sequence. The development of Brachypodium as a model species is of particular value in the areas of cell wall and biomass research, where differences between dicots and grasses are greatest. Here we explore the effect of mild conditions of pretreatment and hydrolysis in Brachypodium stem segments as a contribution for the establishment of sensitive screening of the saccharification properties in different genetic materials.

Results: The non-cellulosic monosaccharide composition of Brachypodium is closely related to grasses of agricultural importance and significantly different from the dicot model Arabidopsis thaliana. Diluted acid pretreatment of stem segments produced significant release of sugars and negatively affected the amount of sugars obtained by enzymatic hydrolysis. Monosaccharide and oligosaccharide analysis showed that the hemicellulose fraction is the main target of the enzymatic activity under the modest hydrolytic conditions used in our assays. Scanning electron microscopy analysis of the treated materials showed progressive exposure of fibrils in the stem segments.

Conclusion: Results presented here indicate that under mild conditions cellulose and hemicellulose are hydrolysed to differing extents, with hemicellulose hydrolysis predominating. We anticipate that the sub-optimal conditions for hydrolysis identified here will provide a sensitive assay to detect variations in saccharification among Brachypodium plants, providing a useful analytical tool for identifying plants with alterations in this trait.

No MeSH data available.


Related in: MedlinePlus

Scanning electron microscopy showing the effect of different saccharification condition in Brachypodium stems. Images of untreated (A), pretreated only (B, D, F, and H) and pretreated and digested stems (C, E, G, and I). Images B to E show pretreatment at 90°C (B and C without acid and D and E with 2% H2SO4), and images F to I show pretreatment at 130°C (F and G without acid and H and I with 2% H2SO4).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2577630&req=5

Figure 4: Scanning electron microscopy showing the effect of different saccharification condition in Brachypodium stems. Images of untreated (A), pretreated only (B, D, F, and H) and pretreated and digested stems (C, E, G, and I). Images B to E show pretreatment at 90°C (B and C without acid and D and E with 2% H2SO4), and images F to I show pretreatment at 130°C (F and G without acid and H and I with 2% H2SO4).

Mentions: The effect of different pretreatment conditions in the structure of the Brachypodium stem segments was observed using scanning electron microscopy (SEM). Figure 4 shows sections obtained by splitting the segments longitudinally, in order to observe the vascular elements and epidermis after pretreatment and subsequent enzymatic hydrolysis. Pretreatment at 90°C with or without enzymatic hydrolysis shows no discernable change in the structure of the vascular tissue. After enzymatic treatment the tissue appears slightly disorganised, but no major effect is observed (Figure 4). The pretreatment with 2% H2SO4 at 90°C also shows no obvious changes in the structure of the tissue, but following subsequent enzymatic hydrolysis there are clear changes in structure with thinner and 'flaky' walls apparent in the longitudinal sections. The longitudinal sections show clear alterations when pretreated at 130°C, even in the absence of H2SO4. When the segments are pretreated at 130°C in the presence of acid, fibrous material is exposed in the surface of the material (Figure 4). Similar exposure of fibrous cell wall material has been shown in barley hull, particularly at the level of epidermis [18].


Analysis of saccharification in Brachypodium distachyon stems under mild conditions of hydrolysis.

Gomez LD, Bristow JK, Statham ER, McQueen-Mason SJ - Biotechnol Biofuels (2008)

Scanning electron microscopy showing the effect of different saccharification condition in Brachypodium stems. Images of untreated (A), pretreated only (B, D, F, and H) and pretreated and digested stems (C, E, G, and I). Images B to E show pretreatment at 90°C (B and C without acid and D and E with 2% H2SO4), and images F to I show pretreatment at 130°C (F and G without acid and H and I with 2% H2SO4).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2577630&req=5

Figure 4: Scanning electron microscopy showing the effect of different saccharification condition in Brachypodium stems. Images of untreated (A), pretreated only (B, D, F, and H) and pretreated and digested stems (C, E, G, and I). Images B to E show pretreatment at 90°C (B and C without acid and D and E with 2% H2SO4), and images F to I show pretreatment at 130°C (F and G without acid and H and I with 2% H2SO4).
Mentions: The effect of different pretreatment conditions in the structure of the Brachypodium stem segments was observed using scanning electron microscopy (SEM). Figure 4 shows sections obtained by splitting the segments longitudinally, in order to observe the vascular elements and epidermis after pretreatment and subsequent enzymatic hydrolysis. Pretreatment at 90°C with or without enzymatic hydrolysis shows no discernable change in the structure of the vascular tissue. After enzymatic treatment the tissue appears slightly disorganised, but no major effect is observed (Figure 4). The pretreatment with 2% H2SO4 at 90°C also shows no obvious changes in the structure of the tissue, but following subsequent enzymatic hydrolysis there are clear changes in structure with thinner and 'flaky' walls apparent in the longitudinal sections. The longitudinal sections show clear alterations when pretreated at 130°C, even in the absence of H2SO4. When the segments are pretreated at 130°C in the presence of acid, fibrous material is exposed in the surface of the material (Figure 4). Similar exposure of fibrous cell wall material has been shown in barley hull, particularly at the level of epidermis [18].

Bottom Line: The non-cellulosic monosaccharide composition of Brachypodium is closely related to grasses of agricultural importance and significantly different from the dicot model Arabidopsis thaliana.Diluted acid pretreatment of stem segments produced significant release of sugars and negatively affected the amount of sugars obtained by enzymatic hydrolysis.Scanning electron microscopy analysis of the treated materials showed progressive exposure of fibrils in the stem segments.

View Article: PubMed Central - HTML - PubMed

Affiliation: CNAP, Department of Biology, University of York, Heslington, York YO10 5YW, UK. ldg3@york.ac.uk

ABSTRACT

Background: Brachypodium distachyon constitutes an excellent model species for grasses. It is a small, easily propagated, temperate grass with a rapid life cycle and a small genome. It is a self-fertile plant that can be transformed with high efficiency using Agrobacteria and callus derived from immature embryos. In addition, considerable genetic and genomic resources are becoming available for this species in the form of mapping populations, large expressed sequence tag collections, T-DNA insertion lines and, in the near future, the complete genome sequence. The development of Brachypodium as a model species is of particular value in the areas of cell wall and biomass research, where differences between dicots and grasses are greatest. Here we explore the effect of mild conditions of pretreatment and hydrolysis in Brachypodium stem segments as a contribution for the establishment of sensitive screening of the saccharification properties in different genetic materials.

Results: The non-cellulosic monosaccharide composition of Brachypodium is closely related to grasses of agricultural importance and significantly different from the dicot model Arabidopsis thaliana. Diluted acid pretreatment of stem segments produced significant release of sugars and negatively affected the amount of sugars obtained by enzymatic hydrolysis. Monosaccharide and oligosaccharide analysis showed that the hemicellulose fraction is the main target of the enzymatic activity under the modest hydrolytic conditions used in our assays. Scanning electron microscopy analysis of the treated materials showed progressive exposure of fibrils in the stem segments.

Conclusion: Results presented here indicate that under mild conditions cellulose and hemicellulose are hydrolysed to differing extents, with hemicellulose hydrolysis predominating. We anticipate that the sub-optimal conditions for hydrolysis identified here will provide a sensitive assay to detect variations in saccharification among Brachypodium plants, providing a useful analytical tool for identifying plants with alterations in this trait.

No MeSH data available.


Related in: MedlinePlus